1. Field of the Invention
The present invention relates to a substrate processing apparatus for processing a substrate.
2. Description of the Prior Art
Conventionally, a substrate processing apparatus includes a process chamber that receives a substrate, a gas supply line that supplies gas into the process chamber, and an exhaust line that exhausts gas from the process chamber. The substrate is loaded into the process chamber, and the gas is supplied into the process chamber and exhausted from the process chamber. In this way, the substrate is processed while supplying the gas to the substrate. For several kinds of gas, gas may be preheated prior to its supply into the process chamber in order to increase a gas reaction speed (for example, see Patent Document 1).    [Patent Document] Patent Publication No. H5-295549
However, if the gas supplied into the process chamber is preheated by a preheating unit, metal contamination may occur in the substrate or the process chamber.